DS1 is 3 1/2. He is entirely capable and comfortable with sitting on the toilet. He is dry all the time. He has no communication issues...but he will NOT poop on the potty

What this leads to is constipation, then miralax per the pedi, then small soft turds in his undies 5x a day or even better, he takes them off and sticks them somewhere in his room/around the house

His room stinks like poo now. I dont know what to do. sometimes, he will poop in a small plastic potty in his room during naps, but sometimes he wont. And he is really to tall for that potty anyways!

Help please!!

I posted this under parenting, and then saw the potty training forum.

I also want to add DS1 doesnt have any special needs but we do drive 90 minutes one way to go to a feeding clinic because he has oral sensitivities. Ive just heard so many times he will out grow it about his eating issues (he wont or I wouldnt drive 3 hours for a 30 min therapy session) it makes me afraid he wont outgrow this either.